標籤頁內部主細節頁Xamarin

Question

更新：

我做了一些如SushiHangover建議的更改，我現在沒有收到錯誤，但我的標籤菜單沒有出現。

我想添加一個標籤頁面，如xamarin文檔中所示，但我不斷收到以下錯誤，System.NullReferenceException「對象引用未設置爲對象的實例。」我需要爲每個頁面聲明一個新的對象，還是在使用xaml時自動完成？

這裏是我的堆棧跟蹤，

at Xamarin.Forms.Platform.Android.AppCompat.Platform.LayoutRootPage(Xamarin.Forms.P age page, Int32 width, Int32 height) [0x0005d] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Platform.Android\AppCompat\Plat form.cs:279 
    at Xamarin.Forms.Platform.Android.AppCompat.Platform.Xamarin.Forms.Platform.Android.IPlatformLayout.OnLayout (Boolean changed, Int32 l, Int32 t, Int32 r, Int32 b) [0x00003] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Platform.Android\AppCompat\Platform.cs:196 
    at Xamarin.Forms.Platform.Android.PlatformRenderer.OnLayout (Boolean changed, Int32 l, Int32 t, Int32 r, Int32 b) [0x0000e] in C:\BuildAgent\work\aad494dc9bc9783\Xamarin.Forms.Platform.Android\PlatformRenderer.cs:73 
    at Android.Views.ViewGroup.n_OnLayout_ZIIII (IntPtr jnienv, IntPtr native__this, Boolean changed, Int32 l, Int32 t, Int32 r, Int32 b) [0x00009] in /Users/builder/data/lanes/3415/7db2aac3/source/monodroid/src/Mono.Android/platforms/android-23/src/generated/Android.Views.ViewGroup.cs:3427 
    at (wrapper dynamic-method) System.Object:d59f31f1-b9b6-40ea-9254-a422fe409750 (intptr,intptr,bool,int,int,int,int) 

這裏是我的代碼，

using Xamarin.Forms; 
namespace BSi.Mobile.Events.Views 
{ 
    public partial class MainMasterDetailPage : MasterDetailPage 
    { 
     public MainMasterDetailPage() 
     { 
      InitializeComponent(); 
     } 
    } 
} 

<?xml version="1.0" encoding="utf-8" ?> 
<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms" 
       xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
       xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" 
       xmlns:local="clr-namespace:BSi.Mobile.Events.Views;assembly=BSi.Mobile.Events" 
       prism:ViewModelLocator.AutowireViewModel="True" 
       x:Class="BSi.Mobile.Events.Views.MainMasterDetailPage"> 
    <MasterDetailPage.Master> 
     <ContentPage Title="Default" Padding="10"> 
      <StackLayout> 
      <Button Text="Home" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\MainPage"/> 
      <Button Text="Event Schedule" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\EventPage"/> 
      <Button Text="Floor Plan" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\FloorPlanPage"/> 
      <Button Text="Sponsor/Media Partners" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\SponsorsPage"/> 
      <Button Text="Where To Eat" Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage\FoodNearbyPage"/> 
      </StackLayout> 
     </ContentPage> 
    </MasterDetailPage.Master> 
    <MasterDetailPage.Detail> 
     <TabbedPage> 
      <TabbedPage.Children> 
       <local:MainPage Title="Info" Icon="http://icons.iconarchive.com/icons/graphicloads/100-flat/256/home-icon.png"/> 
       <local:EventPage Title="Sessions" Icon="http://icons.iconarchive.com/icons/graphicloads/100-flat/256/home-icon.png"/> 
       <local:SpeakersPage Title="Speakers" Icon="http://icons.iconarchive.com/icons/graphicloads/100-flat/256/home-icon.png"/> 
       <local:ExhibitsPage Title="Exhibits" Icon="http://icons.iconarchive.com/icons/graphicloads/100-flat/256/home-icon.png"/> 
      </TabbedPage.Children> 
     </TabbedPage> 
    </MasterDetailPage.Detail> 
</MasterDetailPage> 

Answer 1

答案是使用命令參數，是相對於要顯示在標籤頁的頁面。

<?xml version="1.0" encoding="utf-8"?> 
<MasterDetailPage xmlns="http://xamarin.com/schemas/2014/forms" 
       xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
       xmlns:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms" 
       prism:ViewModelLocator.AutowireViewModel="True" 
       x:Class="BSi.Mobile.Events.Views.MainMasterDetailPage"> 
<MasterDetailPage.Master> 
    <ContentPage Title="Default"> 
    <StackLayout> 
     <StackLayout BackgroundColor="{StaticResource iconGray}" Padding="15"  HeightRequest="100"> 
     <Image Source="canfitpro_logo2" HeightRequest="60" HorizontalOptions="Start" VerticalOptions="EndAndExpand" /> 
     </StackLayout> 
     <TableView Intent="Form" HasUnevenRows="True"> 
     <TableRoot> 
      <TableSection Title="Vancouver Fitness Expo"> 
      <ViewCell> 
       <StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal"> 
       <StackLayout.GestureRecognizers> 
        <TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="EventTabbedPage/NavigationPage/MainPage"/> 
       </StackLayout.GestureRecognizers> 
       <Image Source="icon_home_circle" HeightRequest="40"/> 
       <Label Text="Home" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/> 
       </StackLayout> 
      </ViewCell> 
      <ViewCell> 
       <StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal"> 
       <StackLayout.GestureRecognizers> 
        <TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="EventTabbedPage/NavigationEventPage"/> 
       </StackLayout.GestureRecognizers> 
       <Image Source="icon_sessions_circle" HeightRequest="40"/> 
       <Label Text="Sessions" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/> 
       </StackLayout> 
      </ViewCell> 
      </TableSection> 
      <TableSection Title="Resources"> 
      <ViewCell> 
       <StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal"> 
       <StackLayout.GestureRecognizers> 
        <TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage/FloorPlanPage"/> 
       </StackLayout.GestureRecognizers> 
       <Image Source="icon_floormap_circle" HeightRequest="40"/> 
       <Label Text="Floor Plan" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/> 
       </StackLayout> 
      </ViewCell> 
      <ViewCell> 
       <StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal"> 
       <StackLayout.GestureRecognizers> 
        <TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage/SponsorsPage"/> 
       </StackLayout.GestureRecognizers> 
       <Image Source="icon_partners_circle" HeightRequest="40"/> 
       <Label Text="Sponsor/Media Partners" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/> 
       </StackLayout> 
      </ViewCell> 
      <ViewCell> 
       <StackLayout Margin="15, 10, 10, 10" Orientation="Horizontal"> 
       <StackLayout.GestureRecognizers> 
        <TapGestureRecognizer Command="{Binding MenuSelectedCommand}" CommandParameter="NavigationPage/FoodNearbyPage"/> 
       </StackLayout.GestureRecognizers> 
       <Image Source="icon_restaurant_circle" HeightRequest="40"/> 
       <Label Text="Where To Eat" VerticalTextAlignment="Center" Margin="20, 0, 0, 0" Style="{DynamicResource SubtitleStyle}"/> 
       </StackLayout> 
      </ViewCell> 
      </TableSection> 
     </TableRoot>   
     </TableView>   
    </StackLayout> 
    </ContentPage> 
    </MasterDetailPage.Master> 
</MasterDetailPage> 

Answer 2

您可以在XAML中添加TabbedPage孩子是這樣的：

<MasterDetailPage.Detail> 
    <TabbedPage> 
     <TabbedPage.Children> 
      <ContentPage Title="Page 1" Icon="ja.png" /> 
      <ContentPage Title="Page 2" Icon="ja.png" /> 
      <ContentPage Title="Page 3" Icon="ja.png" /> 
     </TabbedPage.Children> 
    </TabbedPage> 
</MasterDetailPage.Detail> 

剛剛替補你的「本地「定製頁面ContentPage

或通過代碼：

public TabsPage() 
{ 
    this.Children.Add (new ContentPage() { Title = "Page 1", Icon = "ja.png" }); 
    this.Children.Add (new ContentPage() { Title = "Page 2", Icon = "ja.png" }); 
    this.Children.Add (new ContentPage() { Title = "Page 3", Icon = "ja.png" }); 
}